West
Nile Virus is now in our headlines and our vocabularies. When any
new challenge enters public health, education
is the key to reasonable reactions and good choices. Who catches
the disease and how? What are experts doing about it? What steps
can you and your familes take to protect yourseves and avoid infection?
Explore what we know and what we're learning about West Nile Virus.
Then make an informed opinion with the activities and questions at
the end of this page.

Mosquitoes: Sometimes More than Just PeskyVirtually every mosquito bite we get may make us itchy but doesn
t cause any other problems. In the tropics some mosquitoes carry dangerous
illnesses like malaria and yellow fever, but these diseases don t live
in the US or Canada. But even up here, if a mosquito bites a person or
animal who is sick, it swallows virus or bacteria that is in the blood.
Then when it bites another person or animal, it can put that virus or
bacteria in that person or animal s blood. Fortunately, most of the diseases
that North American mosquitoes carry don t hurt us, and the itch from
the bite is not from any disease.

But in 1999, a disease arrived in North America that had never been
here before: West Nile Virus. The disease most likely
was brought here in a horse or a human. It's not a new disease. People
have known about it since 1937, and it may have been around centuries
before that. West Nile Virus used to exist only in Africa, West and Central
Asia, and the Middle East. Over time, most people and animals there have
developed resistance to the disease. When West Nile Virus came to America
in 1999, the animals and people here had not been exposed to it before.
Fortunately, people are pretty strong and don t usually even get sick
from it.

West Nile Virus lives in blood. Fortunately, when an infected mosquito
bites a person, usually the person can fight off the disease, and many
people build up antibodies that will kill any new West
Nile Virus that mosquitoes may bring them in the future. But some people
do get sick from West Nile Virus. A few get so sick that they can die.
In 2002, an estimated half-million people were bitten by mosquitoes with
West Nile Virus; 3667 people got sick from it, and 212 died of the disease.
Many of the people bitten by infected mosquitoes now are protected by
antibodies.

Targets for West Nile VirusMosquitoes bite far many more animals than people. West Nile Virus
is far more dangerous for some mammals and many birds than it is for humans.
When horses are bit by an infected mosquito, they get the disease easily,
and a high percentage of them die. The first known case of the disease
in America was a horse in New York in 1999. Since then many more horses
have died from it than people. Also, some birds are in real trouble if
they get bit by infected mosquitoes. Almost every crow that has been exposed
to the virus has died. Blue Jays, in the same family as crows, also get
sick and die easily if they get bit by infected mosquitoes. So far, scientists
have found that more than 140 species of birds can die from West Nile Virus.

Using Pesticides to Stop the Disease
In hopes of stopping the spread of West Nile Virus, many cities and states have
started spraying insecticides in the air to kill mosquitoes. There are two different
kinds of insecticide sprays for mosquitoes, and both affect more species than
the targeted mosquitoes.

Adulticides kill adult mosquitoes. But adult mosquitoes
move around so much that this kind of spray program doesn't work well. Mosquitoes
can fly over 11 miles in a single day, and many move over 20 miles between
their breeding grounds and their feeding areas. So just a day after spraying,
a lot of new adult mosquitoes may fly in from other areas. Insecticides that
kill adult insects also harm other living things. They kill dragonflies and
other insects that eat mosquitoes. The insecticides also kill frogs and fish,
which both eat mosquito larvae and are beneficial in many other ways. And
these pesticides harm many birds, too. In 2000, researchers in New York collected
80,000 dead birds and performed necropsies on over 4,000 of them. Fully 31%
tested positive for West Nile Virus. But pesticide poisoning directly or
indirectly caused the deaths of 48%. Some died in accidents or from trauma
while sickened or dying from pesticide exposure. Others directly from the
poisoning. And even when insecticides were sprayed in the Chicago area in
2002, they still had more cases of West Nile Virus than places in the state
where no spraying was done.

Larvicides kill mosquito larvae, which live in water.
The kind most often used is actually a bacteria called Bacillus thuringiensis. The
strain used to kill mosquitoes kills fly larvae but not other orders of insects.
So it's safe for dragonflies, butterflies, and other insects. Another kind
of larvicide used is a hormone that prevents mosquito larvae from developing
into adults. This may be harmful to other insects as well, and may cause
other ecological problems. Larvicides are not normally used over backyards,
where a great many mosquito larvae grow up.

Insecticides
are not the only ways to control mosquitoes. Healthy populations
of birds, bats, dragonflies and other "mosquito-eating machines" will
get rid of huge numbers of mosquitoes.

How to Protect Against West Nile Virus
Mosquito control is first. The best way to keep mosquitoes from developing in
most neighborhoods is to make sure there is NO standing water anywhere. Gutters,
sandbox toys, unused flower pots, old tires, and open garbage cans are a few
places where mosquitoes lay their eggs. Check them often, and empty out any water.
Mosquitoes may lay eggs in birdbaths, too. If you have one in your yard, make
sure you change the birdbath water every two or three days.

Prevent mosquito bites. Even if no mosquito larvae live in your area, adult
mosquitoes fly in from many other places. So if you live in an area where West
Nile Virus exists, the most important thing is to protect yourself and the
people you know from mosquito bites. Wear long sleeves and long pants when
mosquitoes are around. Insect repellents with DEET work well, but read labels
and use only 10% DEET or less. (Spray only outdoors, and wash off repellent
when you get home. Don't spray repellent on your hands or face, and don't breathe
repellent.)

When you find dead birds, make sure you report them. Call your state or province's
department of natural resources to find out what they'd like you to do with
the dead bird. Some cities and states are no longer testing dead birds for
West Nile Virus if they already know that the disease is in an area; the tests
are very expensive. Where dead birds are actually tested to discover the cause
of death, many times it turns out to be other things, especially pesticides.

The Outlook: Minds at WorkA vaccination to prevent West Nile Virus in horses already exists. Rehabilitators
and people working with captive endangered birds are also using a bird vaccination.
According to several experts, a vaccination for people probably won't be made
because so few people get sick from West Nile Virus; a vaccination may cause
more harm than good.

In the long run, most kinds of animals will develop immunity to
West Nile Virus. But until then, there may be a few years when the disease
kills a lot more birds and other animals. Figuring out how to solve a tricky
problem like this is something we humans are masters at. Information is our
best defense.

1. How does West Nile Virus affect YOU? Is West Nile Virus in your state or
province? What numbers have been reported? To see exactly how many cases of
West Nile Virus have been recorded in the U.S this year, go to:

West Nile Virus hasn't spread as quickly in Canada. Could the reason be because
it is farther north? One person died of West Nile Virus in Ontario in 2002.
The Canadian government is tracking dead birds to keep tabs on the threat.
See:

2. Brainstorm a list of people who have direct connections with West Nile
Virus. Tell what their connections are, and how they might feel about the issue
of spraying or not spraying to kill mosquitoes or their larvae. (Examples:
doctor, veterinarian, wild bird rehabilitator, someone whose family member
has West Nile Virus, ornithologist, hoser rancher, someone wh works at a place
that makes insecticides, someone whose job is applying insecticides, someone
who spends a lot of time outdoors in swampy areas....)